import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {


    private ServerSocket serverSocket = null;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("启动服务器!");
        ExecutorService service = Executors.newCachedThreadPool();
        while (true){
           Socket cilentSocket = serverSocket.accept();
           //创建线程,每个线程服务一个客户端
         /*  Thread t = new Thread(()->{
               try {
                   processConnection(cilentSocket);
               } catch (IOException e) {
                   e.printStackTrace();
               }
           });
           t.start();*/
            //使用线程池
            service.submit(()->{

                try {
                    processConnection(cilentSocket);
                }catch (IOException e){
                    throw new RuntimeException(e);
                }
            });

        }
    }

    //针对一个连接,提供处理逻辑
    private void processConnection(Socket cilentSocket) throws IOException {
    //先来打印一下客户端信息
        System.out.printf("[%s:%d] 客户端上线!\n",cilentSocket.getInetAddress(),
               cilentSocket.getPort() );

        try(InputStream inputStream = cilentSocket.getInputStream();
            OutputStream outputStream = cilentSocket.getOutputStream()){
            //使用Scanner包装一下Inputstream,就可以更方便的读取这里的请求数据了
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            while (true){
                //1,读取请求并解析

                if(!scanner.hasNext()){
                    //如果scanner无法读取出数据,说明客户端关闭了连接,导致服务器这边读取到"末尾"
                    break;
                }
                String request = scanner.next();
                //2,根据请求计算响应
                String response = process(request);

                //3,把响应写回客户端
                //此处可以按照字节数组直接来写,也可以有另外一种写法
                //outputStream.write(response.getBytes());
                printWriter.println(response);
                printWriter.flush();
                //4,打印日志
                System.out.printf("[%s:%d] req = %s; resq = %s\n",cilentSocket.getInetAddress(),
                        cilentSocket.getPort(),request,response);
            }

        }catch (IOException e){
            e.printStackTrace();
        }finally {
            System.out.printf("[%s:%d] 客户端下线!\n",cilentSocket.getInetAddress(),
                    cilentSocket.getPort());
            cilentSocket.close();
        }


    }

    private String process(String request) {

        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server = new TcpEchoServer(9090);
        server.start();
    }

}
